1. Field of the Invention
The present invention relates to modular building systems, and, more particularly, to a modular structural member building system for use in erecting buildings, houses or other structures, including equipment and fabrication methods used in making modular structural members and used in combining modular structural members for building.
2. Description of the Related Art
Currently, there critically exists a need to provide an environmentally sensitive, economical, modular building system which can utilize the minimum of labor skills, provide for a low maintenance, provide for the conservative use of natural resources, and provide flexibility in style and design. However, until the present invention, there has not been provided a total integrated system of structural components that functions as a modular building system of floors, walls, ceilings, trusses, and roof members that can replace other materials conventionally used in frame buildings.
More particularly, there has not been a use of specific integrated materials that form a modular building system capable of eliminating the need to use a wide assortment of conventional materials, such as structural graded lumber, metal devices, seismic plywood panels, plastic non-biodegradable and chemical products. The supply of such conventional and natural building products is being diminished faster than the replenishment rate for these products, due largely to the increasing global demand for buildings and other structures. Hence, conventional building practices are currently inadequate for protecting the quality of life and preservation of natural resources on a global scale. Furthermore, until the present invention, there has not been provided a structural modular building system capable of resolving the interrelated difficulties of fabricating an integrated modular structural member to fulfill the structural and life/safety requirements of each specific material, said member being produced at low cost, having a light weight, being integrated from environmentally sound materials, and being flexibly combined with other modular components in to provide a modular building system.
Providing structural integrity with a consistent quality control of every member of the many components that make up a conventional building system presents difficulties due to the inconsistencies of the quality of graded lumber. Governing agencies, responsible for issuing building codes, have therefore implemented various codes to include additional structural connections and materials which in fact increased the cost, complexity, and difficulty of providing a modular structural member building system. Presently, no one has economically produced structural components with consistent structural integrity, flexibility of style and design, which are capable of being produced and installed in both domestic and international markets. The foregoing difficulty of providing a modular building system is compounded by the life/safety requirements of establishing a general and acceptance approval by the local, state, and national governing agencies; providing criteria, standards, inspections, and quality control of installations; providing performance specifications; and fulfilling the regulations and requirements of approved testing facilities.
Recognized approval ratings for structural members must be established and maintained for a particular modular system. Inspecting the quality of installed structural members is a third difficulty. The quality of structural members actually used in buildings must be ensured by fulfilling recognized approval ratings and inspection procedures in the interest of public safety. Providing sound design principles for structural members is still another difficulty. This entails the economical utilization of structural members in fabricating the various details of buildings while fulfilling all necessary building codes and architectural requirements. Conserving scarce materials and reducing costs while fabricating and using structural members is another difficulty. Environmental -preservation calls for the conservation of resources and materials while providing structural members in a modular building system while also overcoming the foregoing difficulties. The following discussion further illustrates the present need to adequately solve the foregoing interrelated difficulties of providing a low cost, environmentally sound modular structural member building system.
As indicated generally above, a major difficulty in providing modular structural members is ensuring the strength, or structural integrity, of the individual members or panels. A structural member, or sandwich panel, may be considered as a beam with regard to its structural integrity. A beam fails when it is does not have the required structural integrity or strength to safely support a given load condition. The structural integrity of a sandwich panel, or composite structural member, depends on a proper choice of materials for use in the member and on a meticulous control of the methods used to fabricate the materials into a finished structural member.
A sandwich panel, or composite structural member, is fabricated by bonding a core material to two adjacent skins or face sheets using a bonding agent. Thus, the structural integrity of a sandwich panel depends on factors that include the properties of the core material, the properties of the face sheet materials, the properties of the bonding agent, and on the methods used to join these materials. The dimensions of the panel and of the individual elements also impact the structural integrity. The problem of ensuring structural integrity is further compounded by the need to economically provide these materials at the job site in fabricated form.
Expandable honeycomb paper is one type of core material which has been used in fabricating sandwich panels. Such paper is provided in the form of an expandable honeycomb paper web which is expanded to provide a honeycomb core. Honeycomb paper is available from various vendors, including HEXACOMB HONEYCOMB CORPORATION, of Saint Louis, Missouri, and HEXEL, of Dublin, Calif. However, the literature available from these vendors does not appear to resolve the foregoing problems encountered in providing a low cost, environmentally sound, modular structural member building system.
From the standpoint of structural integrity, the sandwich panels or structural members are considered as beams. A beam must be capable of supporting various loads or forces between two or more given points of a building or structure. For a very general treatment of this subject refer to "Technical Service Bulletin H-4"0 published by HEXACOMB HONEYCOMB CORPORATION. However, this reference does not cover situations where structural performance of a panel is critical. In particular, the quality or integrity of the bond between the core and facing skin is not considered or discussed. Also, operational conditions which might adversely affect the behavior of certain grades of core or types of facings are not considered or discussed. The reference recommends separate investigation of these aspects of the problem, as well as actual testing of any panels fabricated for structural use. Thus, the bulletin does not solve any of the interrelated difficulties of providing structural integrity, quality control, approval, testing, inspection, sound design principles, conservation, or reduced costs in a modular structural member building system.
A reference published by HEXEL is entitled "Kraft Paper Honeycomb Commercial Grade--Structural", D.S. 1002 (1970). This reference provides specifications for the expandable honeycomb paper web itself. It does not discuss particular fabrication details or methods of making structural members having a honeycomb core. Similarly, this reference does not adequately address the interrelated difficulties of providing structural integrity, quality control, approval, testing, inspection, design principles, conservation, or reduced costs in structural sandwich panel buildings.
Honeycomb paper is available in either expanded form (i.e., as a "core") or unexpanded form (i.e., as an expandable "web") from vendors such as HEXEL or HEXACOMB. However, each form presents a unique difficulty with economically providing a structural honeycomb core member at a building site. These difficulties are not adequately addressed by either of the foregoing references. For expanded paper cores, shipping costs to the construction site are prohibitively high. This is because expanded cores have a large volume to weight ratio. For unexpanded paper webbing, shipping costs are relatively economical. However, local expansion requires facilities for expanding the paper to structural specifications. In particular, improper expansion of the paper web causes brittleness or other structural weakness in the resulting honeycomb paper core. An improperly expanded core must not be used in a structural member because the member would fail under designed load conditions. These difficulties of economically providing a structurally sound honeycomb core at a local building site have not been adequately resolved prior to the present invention. Accordingly, there is a need to provide for devices and systems for manufacturing modular structural honeycomb core members of relatively high quality and relatively low cost.
One of the present inventors, Robert L. Timbrook, secured U.S. Pat. No. 3,665,662 based on his early research into honeycomb core building panels. This patent is directed to a structural member for use in buildings, but it does not adequately resolve the interrelated difficulties indicated above. For example, there is no discussion of the expansion and transportation difficulties stemming from the use of a honeycomb paper core.
Similarly, the technical and commercial difficulties related to structural integrity, quality control, approval ratings, testing, inspection, sound design principles, and reduced costs are not adequately resolved by a reading of the Timbrook patent disclosure. The present disclosure reflects significant advances based on continued research and development on the part of the present inventors. Accordingly, U.S. Pat. No. 3,665,662 is incorporated by reference into the present patent application.
The International Conference of Building Officials (ICBO), through its subsidiary ICBO Evaluation Service (ICBO ES), Inc., evaluates and establishes acceptance criteria for sandwich panels. The ICBO ES is located in Whittier, Calif. A reference entitled "ACCEPTANCE CRITERIA FOR SANDWICH PANELS" was published by the ICBO ES in 1988, detailing the acceptance criteria as of that date. The criteria are used as a guideline which the ICBO ES requires independent testing authorities to follow when conducting evaluation reports of particular sandwich panel systems. Providers of sandwich panels or sandwich panel building systems must obtain an approved evaluation report from an independent testing authority (approved by the ICBO ES) on a yearly basis.
Evaluation criteria developed by the ICBO ES are based on requirements of the Uniform Building Code, the Uniform Mechanical Code, the Uniform Plumbing Code and related codes. Section 105 of the Uniform Building Code (UBC) is the basis for issuing evaluation reports on sandwich panels and other alternative building materials not specifically covered under the UBC.
Essentially, an evaluation report is designed to ensure that sandwich panels, or structural members, comply with the provisions of the Uniform Building Code and related codes. The ICBO ES may approve structural members if the proposed design is satisfactory and complies with other provisions of the code and that the materials and methods used are, for the purpose intended, at least the equivalent in the UBC in suitability, strength, effectiveness, fire resistance, durability, safety and sanitation. The acceptance criteria are issued to provide interested parties with guidelines on obtaining approved evaluation reports from independent authorities verifying that performance features of the codes are fulfilled.
Briefly, the sandwich panel acceptance criteria require that a proponent of a sandwich panel for evaluation fulfill many technical requirements. These requirements include: choosing panel test options; providing panel descriptions conforming to the panels under test; testing the panels (based on chosen test option) using a recognized testing agency or recognized independent observer; restrictions and miscellaneous criteria applying to actual panel uses; additional fabricator qualifications and procedures; panel identification procedures; and quality control monitoring through recognized inspection agencies. These acceptance criteria further illustrate the interrelated difficulties of providing a low cost, environmentally sound, structural member for use in a modular system for erecting buildings and other structures.
Hence, the acceptance criteria do not resolve the foregoing difficulties of providing modular structural members in an integrated building system. The criteria, if anything, appear to reflect the difficulties of providing structural members in an economical manner capable of successfully performing as an integrated building system. Presently, there has not been provided a structural honeycomb core building panel with the necessary combination of attributes to economically fulfill building requirements and to provide architectural design flexibility. These attributes include structural integrity, modularity, approved evaluation and testing, fabrication methods exhibiting quality control, inspection methods, adequate design principles, environmental conservation, low cost, and desirable building properties.
A modular, honeycomb core structural member has structural properties that vary greatly based on several factors. These factors include, but are not limited to: (1) the properties of the face sheet or skin materials; (2) the properties of the honeycomb core material; (3) the properties of the bonding agent used to join the core to the skins; (4) the fabrication method or process used to effectuate the adhesive bond between the core and skins; and (5) ambient conditions during fabrication. A honeycomb core structural member has other properties that also vary based on the choice of materials and method of fabricating the panels. These properties include, but are not limited to: (1) waterproofing; (2) fire resistance; (3) bug and vermin resistance; (4) fungi-proofing; (5) seismic stressing; (6) sound absorption; (7) insulation against heat or cold; (8) design flexibility; and (9) durability or product life.
As is apparent from the foregoing discussion, the art is still without an economical, environmentally sound modular structural member for use in an integrated building system. Accordingly, it is an object of the present invention to provide an environmentally sensitive, economical, modular building system which can utilize the minimum of labor skills, provide for a low maintenance, provide for the conservative use of natural resources, and provide flexibility in style and design. Another object is to provide a total integrated system of structural components that functions as a modular building system of floors, walls, ceilings, trusses, and roof members that can replace other materials conventionally used in frame buildings.